(Objective-C) Sign a File to Create a .p7s (Detached Signature)

Objective-C example to create a detached signature file (.p7s) for any type file. The signature can be verified by calling VerifyP7S and passing the original filename and the .p7s filename.

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#import <CkoCrypt2.h>
#import <NSString.h>
#import <CkoCertStore.h>
#import <CkoCert.h>

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

CkoCrypt2 *crypt = [[CkoCrypt2 alloc] init];

// Use a digital certificate and private key from a PFX file (.pfx or .p12).
NSString *signingCertSubject = @"Acme Inc";
NSString *pfxFilename = @"/Users/chilkat/testData/pfx/acme.pfx";
NSString *pfxPassword = @"test123";

CkoCertStore *certStore = [[CkoCertStore alloc] init];
BOOL success = [certStore LoadPfxFile: pfxFilename password: pfxPassword];
if (success != YES) {
    NSLog(@"%@",certStore.LastErrorText);
    return;
}

CkoCert *cert = [certStore FindCertBySubjectCN: signingCertSubject];
if (certStore.LastMethodSuccess == NO) {
    NSLog(@"%@",@"Failed to find certificate by subject common name.");
    return;
}

// Tell the crypt component to use this cert.
success = [crypt SetSigningCert: cert];

// We can sign any type of file, creating a .p7s as output:
NSString *inFile = @"/Users/chilkat/testData/pdf/sample.pdf";
NSString *sigFile = @"/Users/chilkat/testData/p7s/sample.p7s";

success = [crypt CreateP7S: inFile p7sPath: sigFile];
if (success == NO) {
    NSLog(@"%@",crypt.LastErrorText);

    return;
}

success = [crypt VerifyP7S: inFile p7sPath: sigFile];
if (success == NO) {
    NSLog(@"%@",crypt.LastErrorText);

    return;
}

NSLog(@"%@",@"Success!");